The invention relates to controllers for generators, such as are used with aircraft engine starters and generators.
It is well known to use generators as starters for motors and engines. For example, in the aerospace industry, DC generators are commonly used as engine starters on small aircraft engines such as gas turbine engines. After the engine is started, the generator typically is used as an electrical power source for the aircraft.
Aircraft manufacturers and governmental regulations have, over the years, gradually increased the demand for more monitoring and control functions to be implemented for these generators, particularly with respect to providing fast and accurate indications of fault conditions to avoid catastrophic generator failures and engine damage. However, space and weight considerations can limit the availability and use of multiple discrete logic circuits. Discrete control circuits also inherently lack central processing control, thus limiting the number of interdependent control functions that can be implemented.
Furthermore, various control and monitoring functions heretofore used with generator discrete controllers can be inadequate or unsuitable for protecting components that can be overstressed or for facilitating acceptable generator operation. For example, linear current limiters for devices subject to current overloads can exhibit large power dissipation, and known switch mode current limiters can deliver excessive currents and therefore not adequately protect interconnect wiring. As another example, it may be desirable in some applications to provide an automatic field flash for the generator without the need for manual pilot control.
The need exists, therefore, for a generator controller that can implement numerous and complex control and monitoring functions to facilitate proper generator operation without a significant increase in cost, space requirements or weight with an increased reliability of generator operation and control.